Commit efe28034 authored by Mingming Cao's avatar Mingming Cao Committed by Jakub Kicinski
Browse files

ibmvnic: Use ndo_get_stats64 to fix inaccurate SAR reporting 



VNIC testing on multi-core Power systems showed SAR stats drift
and packet rate inconsistencies under load.

Implements ndo_get_stats64 to provide safe aggregation of queue-level
atomic64 counters into rtnl_link_stats64 for use by tools like 'ip -s',
'ifconfig', and 'sar'. Switch to ndo_get_stats64 to align SAR reporting
with the standard kernel interface for retrieving netdev stats.

This removes redundant per-adapter stat updates, reduces overhead,
eliminates cacheline bouncing from hot path updates, and improves
the accuracy of reported packet rates.

Signed-off-by: default avatarMingming Cao <mmc@linux.ibm.com>
Reviewed-by: default avatarBrian King <bjking1@linux.ibm.com>
Reviewed-by: default avatarDave Marquardt <davemarq@linux.ibm.com>
Reviewed-by: default avatarSimon Horman <horms@kernel.org>

----
Changes since v3:
link to v3: https://www.spinics.net/lists/netdev/msg1107999.html
-- keep per queue counters as u64 (this patch) and drop off patch 1 in v3

Link: https://patch.msgid.link/20250716152115.61143-1-mmc@linux.ibm.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 0dce6847

drivers/net/ethernet/ibm/ibmvnic.c

+20 −7
Original line number Diff line number Diff line
@@ -2312,8 +2312,6 @@ static void ibmvnic_tx_scrq_clean_buffer(struct ibmvnic_adapter *adapter, 
					  tx_pool->num_buffers - 1 :

					  tx_pool->consumer_index - 1;

		tx_buff = &tx_pool->tx_buff[index];

		adapter->netdev->stats.tx_packets--;

		adapter->netdev->stats.tx_bytes -= tx_buff->skb->len;

		adapter->tx_stats_buffers[queue_num].batched_packets--;

		adapter->tx_stats_buffers[queue_num].bytes -=

						tx_buff->skb->len;
@@ -2647,9 +2645,6 @@ static netdev_tx_t ibmvnic_xmit(struct sk_buff *skb, struct net_device *netdev) 
	}

out:

	rcu_read_unlock();

	netdev->stats.tx_dropped += tx_dropped;

	netdev->stats.tx_bytes += tx_bytes;

	netdev->stats.tx_packets += tx_bpackets + tx_dpackets;

	adapter->tx_send_failed += tx_send_failed;

	adapter->tx_map_failed += tx_map_failed;

	adapter->tx_stats_buffers[queue_num].batched_packets += tx_bpackets;
@@ -3452,6 +3447,25 @@ static int ibmvnic_reset(struct ibmvnic_adapter *adapter, 
	return -ret;

}



static void ibmvnic_get_stats64(struct net_device *netdev,

				struct rtnl_link_stats64 *stats)

{

	struct ibmvnic_adapter *adapter = netdev_priv(netdev);

	int i;



	for (i = 0; i < adapter->req_rx_queues; i++) {

		stats->rx_packets += adapter->rx_stats_buffers[i].packets;

		stats->rx_bytes   += adapter->rx_stats_buffers[i].bytes;

	}



	for (i = 0; i < adapter->req_tx_queues; i++) {

		stats->tx_packets += adapter->tx_stats_buffers[i].batched_packets;

		stats->tx_packets += adapter->tx_stats_buffers[i].direct_packets;

		stats->tx_bytes   += adapter->tx_stats_buffers[i].bytes;

		stats->tx_dropped += adapter->tx_stats_buffers[i].dropped_packets;

	}

}



static void ibmvnic_tx_timeout(struct net_device *dev, unsigned int txqueue)

{

	struct ibmvnic_adapter *adapter = netdev_priv(dev);
@@ -3567,8 +3581,6 @@ static int ibmvnic_poll(struct napi_struct *napi, int budget) 


		length = skb->len;

		napi_gro_receive(napi, skb); /* send it up */

		netdev->stats.rx_packets++;

		netdev->stats.rx_bytes += length;

		adapter->rx_stats_buffers[scrq_num].packets++;

		adapter->rx_stats_buffers[scrq_num].bytes += length;

		frames_processed++;
@@ -3678,6 +3690,7 @@ static const struct net_device_ops ibmvnic_netdev_ops = { 
	.ndo_set_rx_mode	= ibmvnic_set_multi,

	.ndo_set_mac_address	= ibmvnic_set_mac,

	.ndo_validate_addr	= eth_validate_addr,

	.ndo_get_stats64	= ibmvnic_get_stats64,

	.ndo_tx_timeout		= ibmvnic_tx_timeout,

	.ndo_change_mtu		= ibmvnic_change_mtu,

	.ndo_features_check     = ibmvnic_features_check,